Arrangement for components included in mobile hydraulic equipment

ABSTRACT

A control system for control of components in mobile hydraulic equipment, the control system being in the form of a CAN system and comprising modules controlling the components and a bus connection. A signal mirroring unit is provided via which the modules are connected to the bus connection. The signal mirroring unit reflects signals generated internally in the module back to the module and prevents the signals from appearing on the bus connection, at least during an activation phase. This allows the control system to operate disruption free.

TECHNICAL FIELD

The invention can be used for hydraulic components intended to be usedas building elements for mobile hydraulic equipment. As examples ofhydraulic components, mention can be made of hydraulic valves, controllevers, hydraulic cylinders, hydraulic motors etc. In one exemplaryembodiment, a hydraulic valve is controlled with a control leverequipment and the valve effects oil flow or oil pressure depending onthe control. Such control systems can be included in forest machinery inwhich the hydraulics can be used for timber loading, control etc. Otherexamples are mining machinery, and various types of other loadingmachines, e.g. trucks with buckets, pallet lifters etc. Further examplesare working baskets, lifting machines, agricultural machinery, andmining equipment etc.

In the equipment user is made of the standardized CAN system (ControllerArea Network) as a control and monitoring system. The CAN systemincludes a number of nodes or modules which can communicate with oneanother via a two-wire or a several wire bus connection in the controland monitoring system, which is characterized by series communication onthe bus communication. The module can comprise master and slave modules.Reference is also made, quite generally, to inter alia said standardwith the designation ISO 11898.

BACKGROUND OF THE INVENTION

State of The Art

It is already known to use the CAN system in connection with vehiclesand mobile equipment. From the publication dated 30-03-1994 fromHoneywell Micro Switch Division, it is known to provide a specialprogram in the system in order, after restarting in the system, to makethe various modules work with a bit speed fixed by or in the system.Among other things, a special NOOP message is transmitted on the busconnection upon restarting. A special elimination bit in this connectionis initiated in a control register in the system, which causes thetransmitter in question to terminate its message, irrespective ofwhether acknowledgement is received or not. The master module mustsubsequently check whether there is a NOOP acknowledgement on theconnection. If no such acknowledgement appears on the connection, themaster module repeats the check. If the acknowledgement exists, themodule takes this as confirmation that the connection is in operation,whereupon other nodes can adjust themselves to the correct bit speed orcorresponding parameters.

It is possible, in a conventional manner, to prevent the CAN circuitfrom carrying out transmission on the bus connection in association withthe restarting. This can take place, e.g., by the output in questionfrom the CAN circuit being programmed to make this possible. In thismanner, the CAN circuit can be made to listen to the bus without the CANcircuit transmitting an error message or acknowledgement bit on the busconnection in question. When the CAN circuit receives a message, thistakes place at a bit speed which can be set with certain parameters andwhich can be adjusted to make possible reception of the bit speedapplicable in the system. In this manner, the CAN circuit cancommunicate on the connection without disrupting or corrupting thecommunication on the connection by working with incorrect parameters/bitspeed. It is to be noted in this case that the rules of the CAN systemstate that one priority field in the CAN system may not be used by twomodules simultaneously. In order to avoid an error message if two ormore modules are transmitting simultaneously, this must be counteractedwith the aid of rules in the software and programs of the CAN system(cf. above).

SUMMARY OF THE INVENTION

Each special arrangement in the system programming complicates thesystem and its application. There is a need to utilize the basicprinciples for the CAN system and to make these work in situations whichwere not presupposed from the outset by the original system builders ofthe CAN system. The invention solves this problem, among others, andproposes that the modules or the nodes themselves are made to appearexactly in the manner which was envisioned when the system of rules wasset up for CAN.

There is also a need that installations exchange, addition and reductionof components in assembled mobile hydraulic equipment is to betechnically simple for the system builders of the mobile equipment. Thesuppliers of individual (hydraulic) components are to be able to makeavailable their products to the system builders without comprehensiveand individual program adjustments for the system having to be made whenmodifications, improvements etc. are to be carried out. The inventionalso solves this problem.

The suppliers of hydraulic components according to the above are able tofurther develop further their products and carry out service (exchange,repair etc.) on existing hydraulic equipment without giving rise toreprogrammings in the CAN system of the equipment. The invention solvesthis problem also.

The problem in using programming to prevent the module in question fromtransmitting an error message or acknowledgement bit in the situationsin question is that such a proposal requires that one of the modules isalready communicating on the bus connection when the module attempts togain access to the bus connection after restarting. This, in turn,requires that the party responsible for the system in some way makesavailable the parameter/bit speed which applies in the functioning stagein question. The module in question of the modules in the system musttherefore state the parameters in question which can be checked by othermodules before these become active on the bus. In a first exemplaryembodiment, it is not sufficient that there is only one module which istransmitting since the module in question, on its transmission, does notreceive any acknowledgement bit from a passive module. For the singletransmitter this is not a large problem since the rules in the CANsystem are such that the module which is transmitting repeats thetransmission until it receives an acknowledgement bit. For the module orthe modules which passively receive the transmitted message, it isinterpreted as an error if an acknowledgement bit is not detected. As aresult of this, the respective receiver will generate an error message,which means that the message, which in reality is transmitted correctlyfrom the transmitting module, is interpreted as an error by therespective receiving module and is therefore automatically rejectedaccording to applicable rules for the CAN system. This gives rise to themodule being disconnected from the bus after a certain time. The modulewhich is using the CAN system cannot distinguish this case from the casewhere an incorrect bit speed or another parameter was selected. Themodule is therefore compelled to leave the bus connection in spite ofthe fact that the module had the correct bit speed or correspondingparameter and would have been able to be connected to the bus. Theinvention aims to solve this problem also.

It can be considered characteristic of an arrangement which solves theproblems indicated above that the respective control and/or monitoringmodule in question is connected or connectable to the bus connection viaa signal-mirroring unit and/or a rule-infraction eliminator whichensures that there is disruption-free and/or collapse-free systemfunctioning even in the activation or connection situations, e.g. systemrestarting.

Further developments of the inventive idea emerge from the subsequentsubclaims.

By means of what is proposed above, a monitoring and checking, definedby the supplier, of the adaptation of the system to various activationand connection situations is made available. Modifications and furtherdevelopments of components can be implemented in an already completedmobile hydraulic equipment and in the new manufacture of such hydraulicequipment. The rule-infraction eliminator can be adapted to anymodifications and further developments in the construction and functionsof the system and the equipment.

BRIEF DESCRIPTION OF THE DRAWINGS

A for the moment proposed embodiment of an arrangement which has thecharacteristics which are significant of the invention is to bedescribed below with simultaneous reference to the attached drawing inwhich:

FIG. 1 shows an exemplary embodiment of the construction of the moduleand its connection to an appropriate component for mobile hydraulicequipment, and

FIG. 2 shows a constructive exemplary embodiment of hydraulic equipmentwith a CAN system

DETAILED DESCRIPTION OF THE INVENTION

In the figure, one of the parts in a CAN system involved in theinvention has been shown. Designations which are not described, e.g. onoutputs and inputs of the system and components thereof, have beenallowed to remain in order to better to refer to the known standardizedCAN system.

In the figure, one module or one node 1 has been shown in its entirety,while two other modules/nodes 2 and 3 have been shown drawn in in brokenlines. The modules can communicate with one another in a known mannerand/or with any overriding module via a bus connection. The modules canbe constructed essentially identically, or have different constructionsdepending on the equipment or pieces of equipment the respective moduleis to control and/or monitor.

The module 1 includes a processor 5 with an integrated CAN circuit 6.The processor and the CAN circuit include a number of connection lines 7and 8. The processor and the CAN circuit control and monitor equipment 9which can include equipment parts 9a, 9b. The equipment can include alever, the deflection of which is to bring about a hydraulic flow in ahydraulic valve. The flow can be more or less proportional to theposition of the lever. The lever and valve are, in this case, capable ofbeing integrated in an assembled mobile hydraulic system according tothe above. The normal case with the lever is that the deflectionproduces a flow proportional to the deflection. In such a case, thelever controls the speed of a cylinder which is included or the rotationof a motor. The deflection can also give a position. Normally, thehydraulic flow is controlled and some type of servo control is oftenintroduced. The control lever deflection can also be intended to act ona number of cylinders, and so the deflection can, e.g., cause a movementof a loading hook on a crane, which movement can adopt a givendirection. The construction of the crane may require activation of anumber of cylinders in order to obtain the correct type of movement. Itis also possible in robot-like cases to effect movements which arestored in a memory and where the activation in question arises by thestored control commands being fed out to the valves included in thesystem.

A crystal oscillator circuit 10 and a power supply unit 11 also belongto the module according to the figure. Included, moreover, is asignal-mirroring unit 12, via which the CAN circuit 6 is connected tothe bus connection 4. In the exemplary embodiment, a communicationcircuit 13 is also utilized, and the unit 12 is in this case connectedboth to the CAN circuit and the communication circuit. The unit 12 isthus inserted between these circuits in the present case. Thefunctioning of the unit 12 can be continuously connected/connectable orconnected or connectable only instantaneously in certain activationand/or connection situations. The instantaneous connection function issymbolized by 14. Upon the temporary uncoupling of the mirroringfunction of the unit 12, the CAN circuit is connected directly to thecommunication circuit, cf. 13', which relates to a previously knownconnection function. The switching function can be controlled e.g. fromthe circuit 13. The unit 12 can thus have an active influence on thedata which is transmitted between the circuits 6 and 13, in certaincases, e.g., on starting, while in normal operation it has negligible orvery little influence. Such an influence can be constituted by a delaywhich occurs when the signal has to pass through the unit (3-25nanoseconds).

According to the idea of the invention, the CAN circuit 6 can listen tothe bus without the CAN circuit itself transmitting an error message oran acknowledgement bit on the bus connection. In this manner, it canadapt itself to the bit speed prevailing in the system or anotherparameter in a known manner.

According to the invention, logic is utilized in the eliminator. In oneexemplary embodiment, logic circuits 15, 16 and 17 which are known perse are included.

The arrangement according to FIG. 1 functions as follows.

By virtue of a NOOUT signal being set high, CANTXO signals from the CANcircuit 6 are prevented from reaching the driving stage 13 (is equal toC250T) and further out on the connection 4. In certain exemplaryembodiments, the TXO output in question can be made inactive, as aresult of which there is no CANTXO output signal, even though the CANcircuit assumes that this will take place. The level of the CANTXOsignal is ensured with the aid of a resistor R1 which is normally usedto ensure that the module remains inactive out on the bus connection 4when the CAN circuit is for some reason not started or active. In thiscase, the CAN circuit is restarted (reset) when this setting is to bechanged. The reset function is found in some CAN circuits and isappropriate in these. A change from inactive to active state with theaid of the NOOUT signal requires no resetting of the CAN circuit. Withthe NOOUT signal, it is therefore ensured that the module 1 does nottransmit anything on the CAN bus, and, by a change of logic level on theNOOUT signal, the CAN circuit can gain access to the bus connectionwithout resetting and/or reprogramming of the CAN circuit having to becarried out. According to the above, it is not sufficient to prevent theCAN circuit from obtaining access to and communicating out on the CANbus in the event that there is no other module connected to the busconnection and the acknowledgement bit is reflected with what is beingtransmitted on the bus connection. By virtue of the LOOP signal beingset low, the CANTXO signal can be generated at the RXO (CANRXO) output.The normal communication on the CAN bus connection is then supplied tothe driving stage 13 (P82C250) and via the logic unit 15 (IC1) thissignal gains access to RXO (CANRXO) which can then be detected by theCAN circuit. When a complete message has been received, the CAN circuit6 transmits according to the rules an acknowledgement bit on TXO(CANTXO) which, with the aid of the NOOUT signal and the logic circuit16 (IC2), prevents the signal in question (acknowledgement) from comingout on the bus connection 4. With the aid of the LOOP signal and thelogic units 15, 17 (IC1 and IC3 respectively), this signal willnevertheless remain at the RXO (CANRXO) connection, as a result of whichthe CAN circuit will according to the rules confirm the message, inspite of the fact that the acknowledgement bit has not been out on thebus.

The unit 12 described also affords the advantage that in the event that,the CAN circuit thinks that there is an error in the communication, theerror message transmitted from the CAN circuit can be received in returnin a manner which the circuit expects, according to the rules in anormally functioning system.

In a preferred embodiment, the system is arranged in such a manner thatthe modules do not become active immediately after they have noted thatthe bit speed or corresponding parameter is correct. In the casedescribed, a single transmitting module will automatically effecttransmission if it does not detect the acknowledgement bit. Normally,all modules do not start at the same time, for this reason a messagemust remain on the bus until all modules have managed to pick up themessage. There are different prerequisites in different types of CANcircuits. In one type of circuit, it would be possible for a receivedmessage to be judged to be correct even though no acknowledgement isreceived. In such a case, the module in question is allowed to becomeactive on the bus even though the acknowledgement bit is missing. Othererrors arising in the signal exchange can be a result of incorrect bitspeed, or incorrectness in another parameter concerned, For this reason,the module in question cannot be allowed to become active on the busconnection in the lastmentioned case. In a preferred embodiment, thetask of the unit 12 is to reflect internally the transmittedacknowledgement bit on reading in by the bus connection so that areceiving module interprets the message received as a correct message,in spite of the fact that the acknowledgement never appeared on the busconnection.

In certain cases, the unit 12 prevents transmitted messages coming outon the bus connection. The unit 12 can also feedback or reflect anacknowledgment bit generated by the CAN circuit and prevent it beingtransmitted on the bus connection. The unit 12 thus has two functions.One function prevents transmitted bits coming out on the bus connectionand a second function internally reflects what is transmitted and wouldhave come out on the bus connection if the unit 12 had not preventedthis. Moreover the unit is transparent for signals appearing from thebus connection. In this manner, simple CAN circuits can pick up anotherwise correct message even though no acknowledgement bit hasappeared on the bus. It is to be noted in this connection that atransmitting module in the CAN system receives the acknowledgement ofits own transmitted message. The module which transmits the messageitself puts a recessive bit out on the bus connection, which bit can bewritten over by other modules by placing a dominant acknowledgement biton the bus connection. The acknowledgement is made by all those whichreceived an error-free message.

In the construction according to the figure, use is made of a 68HC05x4processor with a CAN circuit assembled with the processor to form anintegrated circuit. The processor 5 comprises member HC705X4 in FIG. 1.The CAN-circuit or CAN controller is integrated in HC705X4 and issymbolized with 6. The CAN controller communicates with electricaldigital signals via the connections or pins 16 TXO and 19 RXO and canalso use connections or pins TX1 and RX1 together with connections orpins VDDH 21 and USSI 18. Circuit 13 copies the signals from TX to CH/CLand back to RX in order to adapt the signals TX and RX to therequirements existing on bus 4 (CH/CL). Connections and disconnectionsof the signal reflection function are prosecuted by means of the signalsNOOUT and LOOP, which are obtained from connections or pins 22 of theprocessor 5. The decision of the reflection operation is executed by theprocessor 5 (see above). Alternatively, when a circuit other than 82C250is used, the decision can be made by circuit 13. Member 13 can beconnected in the same way as the circuit 13', which represents the priorart connection and which is not included or existing in the presentinvention as such. Member 80 is a serial memory which stores parameterssuch as baud rate, the kind of messages which are to be received, stepoperations, node numbers, and so on. In the shown embodiment theoscillator 10 provides a predetermined frequency, for example 16 MHz, tothe processor 5 (the circuit IC5 HC705X4). On the unit, there are fourconnections for connection to the bus line. The four connections havethe designation TXO, TX1 (transmitting) and RXO, RX1 (receiving)respectively. In simple systems, these CAN connections can be connecteddirectly to the bus connection 4. Usually, however, a special circuit 13is utilized, in this case 82C250 from Philips, which deals moreefficiently with the electrical requirements made on the communication.With this circuit, it is normally necessary to use only TXO and RXO inthe respective application in question. The signal out from the CANcircuit comes on the TXO connection and the TX1 connection.

Normally, one of these signals is sufficient to deal with transmissionon the CAN connection 4, especially if use is made of a driving stage ofthe 82C250 type. For reading off the CAN connection 4, use is made ofinputs RX0 and RX1, where RX0 is the input for CAN and RX1 is achange-over reference to RX0. RX1 is normally connected to 2.5 voltswhich means that RX0 over the voltage on RX1 is interpreted as "1" andunder RX1 is interpreted as "0". A crystal oscillator 10 indicated inthe figure is required in order to make the processor 5 function.

In FIG. 2, an exemplary embodiment with a lifting crane for differenttypes of goods is shown. The equipment described is somewhat simplifiedand includes slightly fewer components than is normal in order that thedescription of the principle is clear. In order to move the crane, thereare, in this case, four motors 50 which lift and lower a main jib 54,51, which in turn lifts and lowers an outer boom 55. A rotating motor 52on the boom 55 rotates a gripping head 56 and a cylinder 53 which opensand closes a gripper 57. The motors are controlled by an oil flow beingsupplied on one or the other side of the respective motor via two hosesor pipes. In this manner, the motors can be made to go forwards orbackwards.

The cylinder 50 is controlled by a hydraulic valve 62 via hoses 58. Thecylinder 51 is controlled by the flow from a valve 63. The rotatingmotor 52 is controlled via hoses 60 from a valve 64 and the cylinderwhich opens and closes the gripper is controlled via hoses 61 from avalve 65. The hydraulic valves are of known type, e.g. L90 or K170,which in principle include a housing with a round ground slide. As aresult of the geometrical shaping of the slide and the housing, it ispossible to obtain a given flow out of the connected hoses. The oilwhich is controlled by the slide is obtained from a pump 70 via the line72 to a valve block, which consists of two valve sections 62 and 63. Aline 71 runs from the valve block with return oil to a tank, from whichthe pump collects its oil for pumping out. The pressure and return lineto the block with the sections 64 and 65 are not shown for the sake ofclarity.

The slide in the valve section can be acted on directly by a lever. Inthe present case, there are electronics which, via an electric drivingstage, act on the valve so that the slide can be displaced. This cantake place by means of an electromagnet which drives the slide directlyor via a servo stage which drives a smaller oil flow which in turn actson the slide. Other solutions are also possible, such as motors whichopen and close a servo valve or drive the slide directly or via anotherunit which can act on the flow to the motors.

The driving electronics in question have a microprocessor which, via aCAN communication according to the above, can be controlled andcommunicate with other equipment. Electronics 66, 67, 68 and 69 areincluded in each valve section. All valves or groups of valves areconnected to a CAN bus 73. This bus normally consists of a twisted pairwith ground reference for the communication, and also a power feed inorder to drive the processor and the driving electronics. In certaincases, the power feed and the bus line are separate. Alternatively,there are several power feeds.

The valves are normally controlled by some type of handle 74 and 75. Thenumber of control handles included depend on how many degrees of freedomit is desired to control simultaneously and whether it is to be possibleto control the equipment from several different positions without movingthe control handle around. When a handle is operated, the size of thedeflection will be transmitted as a message. By virtue of the valveelectronics being connected to such a message, the valve electronicswill each receive their own message by lever deflection, the electronicsoperate the slide to the same extent as the lever is operated.

The CAN bus 73 can also be extended and connected to other electronics79 which can have an overriding control of the system or be used forexchange of information with the user via buttons and/or an screen withtext and/or image. It can also be envisioned that the CAN bus isextended down to the pump via 78 or that the pump has a separate busline 77 to the electronics unit 79. If the pump is equipped with controlelectronics which control the functioning of the pump, it is possible tooptimize the functioning of the pump in relation to the demand which ismade in the system for the pressure and the flow which the pump shoulddeliver. It is also possible for the pump to advise the system if it isnot dealing with the demand of the system in certain periods so that thesystem can adapt its demand to what the pump can offer at the time.

On starting, there is some function or unit in the system which isresponsible for the functioning, e.g. the electronics 79, or, if theseare not there, the handle 75 or 74. This unit, which is programmed forthis function, begins to communicate with other units on the bus. Withthe aid of the described solution, all correctly set parts will be ableto communicate without disruption, i.e., without being disrupted by anincorrectly set module. If, e.g., the electronics 68 are exchanged fornew and the latter is incorrectly set, the system will be able tofunction so that it is still possible to work with the electronics units66, 67, and 69 and valves connected to these. It is also possible forthe electronics 68 to make a number of attempts and in this manner findits way to the correct bit frequency without corrupting thecommunication of the other modules.

The invention is not limited to the embodiment shown in the above as anexample but can be subjected to modifications within the scope of thefollowing patent claims and the inventive idea.

I claim:
 1. A control system for control of components in mobilehydraulic equipment, said control system being in the form of a CANsystem and comprising:modules controlling said components; a busconnection; and signal mirroring means, via which said modules areconnected to said bus connection, for reflecting signals generatedinternally in one of said modules back to said one of said modules andfor preventing said signals from appearing on said bus connection, atleast during a connection phase, whereby said control system functionsdisruption free.
 2. The control system according to claim 1, whereinsaid signal mirroring means is transparent for signals from said busconnection to said modules.
 3. The control system according to claim 1,further comprising further means for preventing said modules fromsending outgoing signals on said bus connection.
 4. The control systemaccording to claim 3, wherein said further means prevents one of saidmodules from transmitting on said bus connection until said one of saidmodules is set to the parameters of said control system.
 5. The controlsystem according to claim 1, wherein said signal mirroring meansgenerates an acknowledgement bit to one of said modules when messagesreceived by said one of said modules via said bus connection are notfollowed by an acknowledgement bit.
 6. The control system according toclaim 1, wherein said connection phase includes restarting said controlsystem, and connecting, disconnecting or exchanging components in saidsystem.
 7. The control system according to claim 1, wherein each saidmodule comprises a processor with an associated CAN circuit; andacommunication effecting unit, wherein said signal mirroring means isconnected to said processor and said communication effecting unit. 8.The control system according to claim 7, wherein said CAN circuitfurther comprises:first and second outputs assigned to outgoingcommunications; first and second inputs assigned to incomingcommunications; a third connection for control of said signal mirroringmeans, whereby said signal mirroring means prevents said first outputfrom reaching said bus connection.
 9. The control system according toclaim 7, wherein said signal mirroring means further comprises means forreflecting an error message generated by said CAN circuit back to saidCAN circuit, whereby said error message does not appear on said busconnection.
 10. The control system according to claim 1, furthercomprising a resistor arranged to ensure said one of said modules isinactive on said bus connection when said one of said modules has notbeen started or is not active.
 11. The control system according to claim8, wherein said CAN circuit further comprises a fourth connection forcontrolling said signal mirroring means to reflect said first output ofsaid CAN circuit to said first input of said CAN circuit.
 12. Thecontrol system according to claim 8, wherein said communicationeffecting unit is connected to said bus connection, and said signalmirroring means comprises:a first logic circuit receiving an first inputfrom said bus connection via said communication effecting unit andoutput connected to said first input of said CAN circuit; a second logiccircuit receiving an input control signal from said third connection andan input from said first output of said CAN circuit; and a third logiccircuit having an input from said first output of said CAN circuit andfrom a second control signal output from said fourth connection, and anoutput to a second input of said first logic circuit; wherein saidacknowledgement bit is generated at said first output of said CANcircuit and is prevented from appearing on said bus connection by saidinput control signal, and said acknowledgement bit appears at said firstinput to said CAN circuit via said first and third logic circuitscontrolled by said second control signal.
 13. The control systemaccording to claim 7, wherein when said CAN circuit detects an error ina message received and transmits an error message as a result, the errormessage is received in a normal manner even though said error messagehas not been transmitted on said bus connection.
 14. The control systemaccording to claim 1, wherein each said module is not active, afterbeing set to system parameters, until a transmitting module in saidsystem retransmits its message.
 15. The control system according toclaim 1, wherein said signal mirroring means is only active in saidconnection phase.
 16. The control system according to claim 14, whereinsaid signal mirroring means allows normal system functioning after saidmodule becomes active.
 17. A control system for control of components inmobile hydraulic equipment, said control system being in the form of aCAN system and comprising:modules connected to a bus connection in saidcontrol system, each said module having a receiving and a transmittingstate; an acknowledgement generator arranged in each said module andgenerating an acknowledgement signal inside said module, each saidmodule being arranged to reflect said acknowledgement signal inwardly sosaid acknowledgement signal does not reach said bus connection.
 18. Acontrol system according to claim 17, wherein said acknowledgementgenerator is arranged between a CAN circuit and said bus connection andfunctions via a mirroring function.
 19. A control system according toclaim 18, wherein said acknowledgement generator is integrated in saidCAN circuit.
 20. A control system according to claim 18, wherein saidacknowledgement generator is integrated in a CAN driver circuit.